Portable gas fractionalization system

ABSTRACT

A portable gas fractionalization apparatus that provides oxygen rich air to patients is provided. The apparatus is compact, lightweight, and low-noise. The components are assembled in a housing that is divided into two compartments. One compartment is maintained at a lower temperature than the other compartment. The lower temperature compartment is configured for mounting components that can be damaged by heat. The higher temperature compartment is configured for mounting heat generating components. An air stream is directed to flow from an ambient air inlet to an air outlet constantly so that there is always a fresh source of cooling air. The apparatus utilizes a PSA unit to produce an oxygen enriched product. The PSA unit incorporates a novel single ended column design in which all flow paths and valves can be co-located on a single integrated manifold. The apparatus also can be used in conjunction with a satellite conserver and a mobility cart.

RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.10/962,194, filed Oct. 7, 2004, which is a continuation-in-part of U.S.patent application Ser. Nos. 10/680,997, 10/681,456, 10/680,885, and10/681,487 all filed Oct. 7, 2003, which are hereby incorporated byreference in their entireties.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to a portable gas fractionalizationsystem, more particularly, to a compact oxygen concentrator that issuitable for both in-home and ambulatory use so as to provide usersgreater ease of mobility.

2. Description of the Related Art

Patients who suffer from respiratory ailments such as ChronicObstructive Pulmonary Diseases (COPD) often require prescribed doses ofsupplemental oxygen to increase the oxygen level in their blood.Supplemental oxygen is commonly supplied to the patients in metalcylinders containing compressed oxygen gas or liquid oxygen. Eachcylinder contains only a finite amount of oxygen that typically lastsonly a few hours. Thus, patients usually cannot leave home for anylength of time unless they carry with them additional cylinders, whichcan be heavy and cumbersome. Patients who wish to travel often have tomake arrangements with medical equipment providers to arrange for anexchange of cylinders at their destination or along the route, theinconvenience of which discourages many from taking extended trips awayfrom home.

Supplemental oxygen can also be supplied by oxygen concentrators thatproduce oxygen concentrated air on a constant basis by filtering ambientair through a molecular sieve bed. While oxygen concentrators areeffective at continual production of oxygen, they are typically largeelectrically powered, stationary units that generate high levels ofnoise, in the range of 50-55 db, which presents a constant source ofnoise pollution. Moreover, the units are too heavy to be easilytransported for ambulatory use as they typically weigh between 35 to 55lbs. Patients who use oxygen concentrators are thus tethered to thestationary machines and inhibited in their ability to lead an activelife. While portable oxygen concentrators have been developed to providepatients with greater mobility, the currently commercially availableportable concentrators do not necessarily provide patients with the easeof mobility that they desire. The portable concentrators tend togenerate as much noise as the stationary units and thus cannot be usedat places such as the theater or library where such noise is prohibited.Moreover, the present portable concentrators have very short batterylife, typically less than one hour, and thus cannot be used continuouslyfor any length of time without an external power source.

From the foregoing, it will be appreciated that there is a need for anapparatus and method that effectively provide supplemental oxygen topatients for both in-home and ambulatory use. To this end, there is aparticular need for a portable oxygen concentrator that is lightweight,quiet, and can supply oxygen continuously for an extended period withoutrequiring an external power source.

SUMMARY OF THE INVENTION

In one aspect, the preferred embodiments of the present inventionprovide a portable gas fractionalization apparatus comprising a PSA unithaving plural adsorbent beds which produce oxygen having a purity of atleast 87%; a compressor connected to supply compressed air to the PSAunit; and a blower which produces an air stream across the compressor.The PSA unit comprises valves operating in accordance with a PSA cyclethat includes a pressure equalization step so as to provide greater thanabout 31% recovery of oxygen from air. Preferably, the valves of the PSAunit are disposed upstream of the air stream across the compressor suchthat thermal load on the PSA valves is reduced. Preferably, thecompressor is a non-reciprocating compressor so as to reduce compressornoise, wherein the compressor is configured to draw ambient air at aflow rate of no more than about 15 slpm.

In one embodiment, the PSA unit comprises two adsorbent beds thatoperate in accordance with a six-step PSA cycle. Preferably, the PSAunit provides between about 31%-38% recovery of oxygen from air andproduces an oxygen having a purity of between about 87%-93%. In anotherembodiment, the compressor comprises a scroll compressor configured tosupply the compressed air to the PSA unit at a flow rate of betweenabout 4 to 9 slpm and at a pressure of about 35 psia while generating anoise level of less than about 35 dB external to the compressor. Incertain embodiments, the apparatus further comprises a heat exchangerwhich cools the compressed air to about the temperature of the ambientair prior to supplying the compressed air to the PSA unit. Moreover, theapparatus may also include a product gas delivery system which deliversoxygen to the patient at a flow rate of between about 0.15-0.75 slpm; amicroprocessor control for recording data on apparatus performance orusage; and an infrared I/O port for transmitting the data to a remotelocation.

In another aspect, the preferred embodiments of the present inventionprovide a portable gas fractionalization apparatus comprising a housinghaving an air inlet and an air outlet wherein the housing is configuredsuch that noise produced exterior to the fractionalization apparatus isno more than about 45 dB. The housing preferably contains componentsincluding a compressor, plural adsorbent beds, a battery having a ratedlife of at least 2 hours. The compressor is powered by the battery so asto draw air into the compressor preferably at a rate of about 15 slpm orless. Moreover, the housing and the components preferably have acombined weight of less than about 10 pounds.

In one embodiment, the apparatus further comprises a blower which isconfigured to draw ambient air through the air inlet to provide coolingfor the components. Preferably, the housing comprises a circuitous airflow passageway for the ambient air to flow through, wherein thecircuitous passageway extends between the air inlet and the air outletand is configured to reduce noise due to air flow. In anotherembodiment, the compressor is preferably a scroll compressor configuredto deliver a feed gas at a flow rate of between about 4 to 9 slpm and ata pressure of about 35 psia while generating a noise level of less thanabout 35 dB external to the compressor. In certain embodiments, theapparatus further comprises a plurality of sound baffles. Moreover, thehousing may also comprise a vibration damper to reduce transfer ofvibrational energy from the compressor to the housing.

In another aspect, the preferred embodiments of the present inventionprovide a method of producing an oxygen rich gas. The method comprisesproviding ambient air to a non-reciprocating compressor, wherein theambient air is drawn into the compressor at a flow rate of less thanabout 15 slpm. The compressor pressurizes the ambient air and deliversthe pressurized air to a PSA unit preferably at a flow rate of betweenabout 4 to 9 slpm. The method further comprises processing thepressurized air in the PSA unit in accordance with a PSA cycle so as toproduce an oxygen rich gas having a purity of between about 87%-93%. Inone embodiment, the PSA cycle includes a pressure equalization step. Inanother embodiment, the PSA cycle is a six-step/two bed cycle.Preferably, the PSA unit operating in accordance with the PSA cycleprovides greater than about 31% recovery of oxygen from the ambient air.In certain embodiments, the method further comprises generating an airstream across the compressor to provide cooling for the compressor.

In another aspect, the preferred embodiments of the present inventionprovide a portable gas fractionalization apparatus comprising pluraladsorbent bed columns mounted side by side and an integral fluid flowmanifold mounted on one end of the columns and comprised of a pluralityof integrated flow passages and a plurality of valves which control flowof fluid through the integrated flow passages to and from the columns.In one embodiment, the apparatus further comprises a circuit boardhaving circuitry which controls the valves. The manifold is preferablydisposed between the circuit board and the one end of the columns.Preferably, contacts on the circuit board are in direct electricalcontact with mating contacts on the valves. In one embodiment, theintegrated fluid flow manifold comprises at least one piloted valve. Inanother embodiment, the integrated fluid flow manifold comprises atleast one water trap positioned therein. The adsorbent columnspreferably comprise one or more feed tubes configured to direct fluid toflow from flow passages in the integrated manifold mounted on one end ofthe columns to an opening in the other end of the columns. In oneembodiment, the integrated manifold comprises an upper plate and a lowerplate, each plate is made of a plastic material.

In another aspect, the preferred embodiments of the present inventionprovide a portable gas fractionalization apparatus comprising acompressor which produces a feed gas; plural adsorbent beds connected toreceive the feed gas from the compressor via a feed gas pathway. Thebeds preferably provide a purified gas and a waste gas from the feed gasand the waste gas is expelled from the beds via a waste gas pathway. Theapparatus further comprises a water trap which traps water condensed inthe fluid pathway to prevent the water from reaching the beds.Preferably, the trapped water is located in the waste gas pathway suchthat the expelled waste gas carries the water away from the beds. In oneembodiment, the water trap is positioned at a lower elevation relativeto the feed gas pathway, wherein gravity causes the condensed water inthe feed gas pathway to flow into the water trap located at the lowerelevation. In another embodiment, the water trap is positioned in alaminated manifold, preferably in the center of a three way junctionformed by airflow pathways to and from a feed valve, an exhaust valve,and a connection to an adsorbent bed.

In another aspect, the preferred embodiments of the present inventionprovide a portable gas fractionalization apparatus comprising a housing,a compressor mounted in the housing on a vibration damping member, and acompressor restraint connected between the compressor and the housingand sufficiently elastically yieldable to non-rigidly fasten thecompressor to the housing. In one embodiment, the vibration dampingmember comprises a grommet having a plurality of ribs formed thereon. Inanother embodiment, the compressor restraint comprises an elastic tetherhaving elongated legs configured with pre-formed bends which extend awayfrom each other. The bends preferably can be pressed toward each otherto straighten the legs and increase the overall length of the compressorrestraint so as to facilitate mounting and removal of the compressorrestraint.

In another aspect, the preferred embodiments of the present inventionprovide an adsorbent bed column comprising an elongated housing; anadsorbent material positioned inside the housing, and a first filterpositioned proximate one end of the housing. The filter preferablycomprises a generally annular member in sealing engagement with thehousing, and a filter portion integrally formed as a single piece withthe annular member. In one embodiment, the annular member comprises asilicone material and the filter portion comprises a woven fabric thatis molded with the annular member. In another embodiment, the firstfilter is adapted to filter particulate greater than about 70 microns.

In another aspect, the preferred embodiments of the present inventionprovide an adsorbent bed column comprising an elongated housing; pluraladsorbents positioned inside the housing; and a first filter comprisedof a frit positioned proximate one end of the housing adjacent at leastone adsorbent. In one embodiment, the column further comprises a secondfilter comprised of a frit positioned proximate the other end of thehousing adjacent at least one adsorbent. Preferably, the first andsecond filters each has a thickness of at least 0.2 inch so as to besufficiently thick to substantially restrain movement of the adsorbentsinside the housing. In another embodiment, the column further comprisesa wave spring positioned against an exterior surface of the first filterso as to apply a substantially even pressure over the first filter.

In another aspect, the preferred embodiments of the present inventionprovide a portable gas fractionalization apparatus comprising acompressor which compresses a gas, such as air, to provide a feed gas;plural adsorbent beds which receive said feed gas and output a purifiedgas and a waste gas; a battery which supplies power to said compressor;and a housing which comprises an ambient air inlet, an ambient airoutlet, and plural compartments. Preferably, a first of the compartmentscontains the adsorbent beds and a second of the compartments containsthe compressor, wherein the compartments significantly inhibit migrationof thermal energy from the second compartment to the first compartment.In one embodiment, the apparatus further comprises an air circulationfan which draws air through the inlet into the first compartment, andthrough the first compartment into the second compartment, the air beingexhausted through the outlet. Preferably, the fan is positioned directlyabove the compressor and produces an air stream directly against thecompressor.

In one embodiment, the housing further comprises a circuitous airpassageway having an upstream portion and a downstream portion throughwhich the air is directed to flow. The upstream portion is preferablypositioned adjacent the first compartment and the downstream portion ispositioned adjacent the second compartment. Preferably, air in thedownstream portion is substantially inhibited from flowing into theupstream portion. In one embodiment, the first compartment furthercontains heat sensitive components including a plurality of valvesinterconnected to the adsorbent beds and a circuit board having controlcircuitry which governs the operation of the valves. In anotherembodiment, the apparatus further comprises a plurality of soundabsorbing baffles positioned along at least a portion of the airpassageway.

In another aspect, the preferred embodiments of the present inventionprovide a portable gas fractionalization apparatus which includes ahousing comprised of a chassis and a shell. The apparatus furtherincludes a plurality of components mounted on and structurally supportedby the chassis. Preferably, the shell covers the components and isremovable from the chassis without removing the components. In oneembodiment, the shell has a plurality of sidewalls, wherein at least onesidewall has a concave or convex section that provides curvature to thesidewall so as to reduce coupling of sound or vibration energy generatedby components in the housing. In another embodiment, the shell has anopening adapted to receive a filter which filters fluid output from theapparatus wherein the filter is accessible from the exterior of theshell. Moreover, the chassis preferably comprises a plurality ofintegral structures adapted to receive and support the components, suchas an integral compressor mount, an integral battery slot, and at leastone integral gas flow passageway. Preferably, the chassis provides anintermediary vibration isolation between the components and the shell ofthe housing. In certain embodiments, the housing further includes ahatch that is removably attached to the shell to provide access to oneor more components therein.

In another aspect, the preferred embodiments of the present inventionprovide a portable gas fractionalization apparatus comprising acompressor which produces a feed gas; plural adsorbent beds connected toreceive the feed gas and produce a purified gas and a waste gas from thefeed gas; a battery; and a conduit connected to deliver the waste gas tothe battery to cool the battery. In one embodiment, the waste gascomprises a nitrogen rich gas. In another embodiment, the battery ispositioned in a battery compartment such that the conduit delivers wastegas to a space between the battery and the battery compartment.Preferably, the battery compartment is comprised of a thermal sleevepositioned around the battery.

In another aspect, the preferred embodiments of the present inventionprovide a method of producing oxygen. The method comprises providing anoxygen concentrator having an air compressor which supplies compressedair to a PSA unit comprising plural adsorbent beds and a plurality ofvalves which control fluid flow to and from the beds; generating an airflow through the concentrator by inputting air through an inlet andoutputting the air through an outlet, such that the air flows along aflow path through the concentrator; and exposing the valves to anupstream portion of the flow path and exposing the air compressor to adownstream portion of the flow path, such that the valves aresubstantially isolated from air that flows through the downstreamportion of the flow path. Preferably, the air flow is generated using anair circulation fan to produce an air stream directly against the aircompressor. In one embodiment, the method further comprises directingthe air flow to flow along a circuitous flow path through theconcentrator. Preferably, the air in the downstream portion of the flowpath is substantially inhibited from circulating back into the upstreamportion. In one embodiment, the method further comprises providing aplurality of sound baffles along at least a portion of the air flow pathto reduce noise generated by the air flow and guide the air flow alongthe flow path.

In another aspect, the preferred embodiments of the present inventionprovide an apparatus for delivering oxygen to a patient. The apparatuscomprises an oxygen concentrator having an oxygen delivery outlet, aflexible tube having a length of at least 10 feet, preferably betweenabout 50 to 100 feet, one end of the tube connected to receive oxygenfrom the outlet, and a conserver which delivers oxygen in meteredamounts in response to sensed breaths of the patient. The conserver ispreferably connected to receive oxygen from the other end of the tubeand delivers the oxygen to the patient. In one embodiment, the conservercomprises a breath sensor adapted to sense breaths of the patient and adelivery valve adapted for delivering oxygen to the patient. In anotherembodiment, the conserver further comprises an attachment member,preferably comprising a clip, adapted for removably attaching theconserver to the patient. In yet another embodiment, the conservercomprises a patient interface for setting oxygen flow rate. Preferably,the patient interface comprises an adjustment member such as a controlknob which selects from a number of discrete flow rates and theadjustment member settings are read by a timing circuit that controlshow long the value is open as a function of the adjustment membersetting. In certain embodiments, the oxygen concentrator is a portableoxygen concentrator having a weight of no greater than about 10 pounds.

In another aspect, the preferred embodiments of the present inventionprovide a mobility cart for transporting a gas fractionalization unit.The mobility cart comprises a frame having a support portion and ahandle portion, wherein the support portion is adapted to receive aportable gas fractionalization unit for transporting the unit inresponse to force on the handle portion. The mobility cart furthercomprises a power supply mounted on the frame, wherein the power supplyhas an A.C. power input, a first power outlet adapted to charge abattery, and a second power outlet adapted to power the unit. In oneembodiment, the handle portion of the frame is configured with anextended position and a retracted position. Preferably, the height ofthe mobility cart is less than about 18 inches when the handle portionis in the retracted position. In another embodiment, the frame has asecond support portion adapted to receive a battery. The second supportportion may include a battery bail configured to mate with a pluralityof guide rails formed on the battery in a manner so as to secure thebattery to the battery bail. Preferably, the first power outlet isadapted to electrically interconnect to the battery when the battery issecured to the battery bail. Moreover, the first power outlet may beadapted to charge a spare battery or a battery mounted inside the unit.In certain embodiments, the power supply also has a third and a fourthpower outlet, each adapted to charge a spare battery. Preferably, thepower supply is sufficient to simultaneously power the unit and powerthe outlets for charging the spare batteries and the battery inside theunit.

In another aspect, the preferred embodiments of the present inventionprovide a wheeled mobility cart comprising a portable gasfractionalization unit; a frame to which the unit is removably connectedfor transporting the unit on the wheels; and a power supply mounted onthe frame. Preferably, the power supply has an A.C. power input, a firstpower outlet adapted to charge a battery, and a second power outletadapted to power the unit. Preferably, the portable gasfractionalization unit comprises an oxygen concentrator, more preferablyan oxygen concentrator that weighs less than about 10 pounds. In oneembodiment, the frame further comprises a handle portion configured withan extended position and a retracted position so as to facilitatestorage of the cart.

In another aspect, the preferred embodiments of the present inventionprovide a battery pack for providing electrical power to a portableoxygen concentrator. The battery pack comprises a generally U-shapedbody defined by a center portion and end portions. The center portionforms the bight of the U and the end portions form the legs of the U.The battery pack further comprises a top portion, a bottom portion, anexterior side portion and an interior side portion. The battery pack hasa longitudinal axis that extends through the top and bottom portions andgenerally parallel to the side and end portions and passing through awall of the interior side portion; a transverse axis that extendsthrough the end portions and parallel to the side, bottom, and topportions and intersecting the longitudinal axis; a lower transverse axisthat is parallel to the transverse axis and passes through the bottomportion and intersecting the longitudinal axis; a central lower lateralaxis that is orthogonal to the longitudinal axis and intersecting boththe longitudinal axis and the lower transverse axis; a first and secondend lower lateral axes that are parallel to the central lower lateralaxis and intersect the lower transverse axis and which pass throughrespective end portions. The battery pack further includes a contactprotrusion extending from the bottom portion by about ⅜ inch or more.The contact protrusion has a first sidewall that is generally parallelto the lower transverse axis and has a length of about 1.5 inches orless. The contact protrusion also has a second sidewall that isgenerally parallel to the central lower lateral axis and has a length ofabout 0.5 inch or less. The distance between the exterior surfaces ofthe end portions measured along the lateral transverse axis is about4.25 inches or less; the distance between the distance between theexterior surfaces of the side portions along the central lower lateralaxis is about 1 inch or less; the distance between the exterior surfacesof the first end portion along the first end lateral lower axis is about1.5 inches or less; and the distance between the exterior surfaces ofthe second end portion along the second end lateral lower axis is about1.5 inches or less. Preferably, the battery pack is substantiallysymmetrical about the central lateral lower axis and asymmetrical aboutthe lower lateral transverse axis. In one embodiment, the battery packfurther comprises a handle portion extending upwardly from an uppersurface of the body of the battery pack. The battery pack can alsoinclude at least one pair of guard rails or clips positioned on theinterior side portion of the battery pack. Preferably, the distancebetween the guard rails is between about 1 and 1.5 inches and the guardrails are configure to engage with a battery bail. In one embodiment,the battery bail is mounted on the oxygen concentrator and/or mobilitycart. In another embodiment, the battery pack further includes a casingand a plurality of battery cells enclosed therein, wherein at least aportion of the battery cells are arranged in a side-by-side array alonga non-linear path.

In another aspect, the preferred embodiments of the present inventionprovide a battery pack for portable oxygen concentrators. The batterypack includes a plurality of battery cells; an asymmetrical housinghaving a U-shaped cross-section, wherein the housing encloses thebattery cells therein and permits the battery cells to be positioned ina side-by-side arrangement along a non-linear path inside the housing; ahandle portion extending from an upper surface of the housing; and acontact protrusion extends from a lower surface, preferably by ⅜ inch ormore, of the housing for mating with power contacts on the concentrator.In one embodiment, the battery cells are selected from the groupconsisting of lithium ion cells, lithium polymer cells, nickel cadmiumcells and nickel metal hydride cells. Preferably, the footprint of thebattery pack has a length that is less than about 4.25 inches a widththat is less than about 1.5 inches when the battery pack is mounted inan upright position in oxygen concentrator.

In another aspect, the preferred embodiments of the present inventionprovide an oxygen concentrator comprising at least one current actuatedflow control valve, and a Pulse Width Modulated (PWM) current sourceconnected to the at least one control valve by providing a PWM signal tothe current source which converts the PWM signal to a valve actuationcurrent. In one embodiment, a first current amplitude corresponding to avalue of PWM duty cycle is sufficient to open or close the valve, and asecond current amplitude which is lower than the first current amplitudeand correspond to a lower PWM duty cycle is sufficient to maintain thevalve in the open or closed state.

In another aspect, the preferred embodiments of the present inventionprovide an oxygen concentrator comprising a controller; at least onecurrent actuated fan; and a Pulse Width Modulated (PWM) current sourceconnected to the fan, wherein the controller actuates the fan byproviding a PWM signal to the current source which converts the PWMsignal to a fan actuation current.

In another aspect, the preferred embodiments of the present inventionprovide an oxygen concentrator comprising a controller; at least onecurrent actuated compressor; a Pulse Width Modulated (PWM) currentsource connected to the compressor, wherein the controller actuates thecompressor by providing a PWM signal to the current source whichconverts the PWM signal to a compressor actuation current. In oneembodiment, the speed of the compressor varies with the amplitude of thecompressor actuation current, wherein the compressor actuation currentvaries with the PWM duty cycle provided by the controller to the PWMcurrent source. In another embodiment, the controller provides specificvalues of PWM duty cycle to the current source which correspond toselectable compressor speeds. In another embodiment, the controllerprovides specific values of PWM duty cycle to the current source whichcorrespond to selectable compressor speeds. In another embodiment, theoxygen concentrator further comprises a compressor speed sensor, whereinthe speed sensor is read by the controller which in turn adjusts the PWMduty cycle provided to the current source to vary the compressoractuation current so as to maintain desired compressor speed duringperiods when the load on the compressor varies.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a portable gas fractionalization system ofone preferred embodiment of the present invention;

FIG. 2 is a perspective view of a portable gas fractionalizationapparatus of another preferred embodiment, which is shown in the form ofan oxygen concentrator;

FIG. 3 is a perspective view of the apparatus of FIG. 2 as seen with theshell removed;

FIG. 4 is a perspective view of the chassis of the apparatus of FIG. 2;

FIG. 5 is a perspective view of the components inside the firstcompartment of the apparatus of FIG. 2, showing a PSA unit;

FIG. 5A is a schematic illustration of a Pulse Width Modulated (PWM)current source being used to control various components of the apparatusof FIG. 5;

FIG. 6 is a schematic illustration of an adsorbent bed column of the PSAunit of FIG. 5;

FIG. 7 is a schematic diagram of gas flow to and from the adsorbent bedcolumn of FIG. 6;

FIG. 8 is a detailed view of the integrated manifold of the PSA unit ofFIG. 5;

FIG. 9 is a schematic illustration of a water trap system incorporatedin the integrated manifold of FIG. 8;

FIG. 10 is a schematic illustration of a piloted valve systemincorporated in the integrated manifold of FIG. 8;

FIG. 11 is a perspective view of the components inside the secondcompartment of the apparatus of FIG. 2, showing a compressor system;

FIG. 12 is a perspective view of a vibration damping member incorporatedin the compressor system of FIG. 11;

FIG. 13 is a perspective view of the components assembled in the housingof the apparatus of FIG. 2;

FIG. 14 is a schematic diagram of a directed ambient air flow throughthe housing of the apparatus of FIG. 2, illustrating a thermalmanagement system of one preferred embodiment;

FIG. 15 is a schematic diagram of a gas flow through the components ofthe apparatus of FIG. 2;

FIG. 16A is a perspective view of the apparatus of FIG. 2, showing anin-line filter integrated in the shell of the apparatus;

FIG. 16B is a detailed view of the in-line filter of FIG. 16B;

FIG. 16C is a perspective view of the apparatus of FIG. 2, showing aremovable hatch;

FIG. 17 is a schematic illustration of a satellite conserver used inconjunction with the apparatus of FIG. 2;

FIG. 17A illustrates the various functionalities including flow settinguser interface incorporated in the satellite conserver of FIG. 17;

FIGS. 18A and 18B are schematic illustrations of a mobility cart used inconjunction with the apparatus of FIG. 2 for transporting the apparatus;

FIG. 19A is a perspective view of a battery pack used to provideelectrical power to the portable gas fractionalization apparatus of FIG.2;

FIG. 19B is an exploded view of the battery pack of FIG. 19A;

FIG. 19C is a rear view of the battery pack of FIG. 19A;

FIG. 19D is a cross-sectional view of the battery pack of FIG. 19A,showing a U-shaped configuration; and

FIG. 19E is a schematic illustration of the battery pack of FIG. 19A.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 schematically illustrates a portable gas fractionalization system100 of one preferred embodiment of the present invention. As shown inFIG. 1, the system 100 generally comprises an intake 102 through whichambient air is drawn into the system, a filter 104 for removingparticulate from the intake air, a compressor assembly 106 forpressurizing the intake air to provide a feed gas, a pressure swingadsorption (PSA) unit 108 which receives and processes the feed gas toproduce a product gas having a higher oxygen content than the ambientair, and a gas delivery system 110 for delivering the product gas to apatient.

Ambient air is drawn through the intake 102 at a relatively low flowrate, preferably no greater than about 15 standard liters per minute(slpm), so as to reduce noise due to airflow through the system. Thesystem 100 further includes a fan 112 that produces an air stream acrossthe compressor assembly 106 also preferably at a relatively low flowrate so as to provide cooling for the compressor assembly 106 withoutgenerating excessive noise.

As also shown in FIG. 1, the compressor assembly 106 includes acompressor 114 and an heat exchanger 116. The compressor 114 ispreferably a non-reciprocating compressor, more preferably a scrollcompressor described in U.S. Pat. Nos. 5,759,020 and 5,632,612, whichare hereby incorporated by reference in their entirety. It is generallyunderstood that a scroll compressor operates by moving a plate such thatit orbits in a single plane relative to a fixed plate. Thus, the use ofa scroll compressor advantageously eliminates reciprocating motion thattends to generate the excessive noise and vibration associated with manyconventional piston compressors. In one embodiment, the scrollcompressor 114 delivers an air flow of between about 4 to 9 slpm at apressure of about 35 psia, while generating a noise level of less thanabout 35 dB external to the compressor. The scroll compressor 114 doesnot require lubricating oil and thus operates in a substantiallyoil-free environment, which advantageously reduces the likelihood ofintroducing oil contaminants into the compressed air. As FIG. 1 furthershows, the compressor 114 works in conjunction with the heat exchanger116 to provide cooled feed gas to the PSA unit 108. In one embodiment,the heat exchanger 116 has a large thermally conductive surface that isin direct contact with the air stream produced by the fan 112 such thatpressurized air traveling through the heat exchanger 116 can be cooledto a temperature close to ambient prior to being supplied to the PSAunit 108.

The PSA unit 108 is configured to operate in accordance with a pressureswing adsorption (PSA) cycle to produce an oxygen enriched product gasfrom the feed gas. The general operating principles of PSA cycles areknown and commonly used to selectively remove one or more components ofa gas in various gas fractionalization devices such as oxygenconcentrators. A typical PSA cycle entails cycling a valve systemconnected to at least two adsorbent beds such that a pressurized feedgas is sequentially directed into each adsorbent bed for selectiveadsorption of a component of the gas while waste gas from previouscycles is simultaneously purged from the adsorbent bed(s) that are notperforming adsorption. Product gas with a higher concentration of theun-adsorbed component(s) is collected for use. Additional backgroundinformation on PSA technology is described in U.S. Pat. No. 5,226,933,which is hereby incorporated by reference.

As shown in FIG. 1, the PSA unit 108 of a preferred embodiment includestwo adsorbent beds 118 a, 118 b, each containing an adsorbent materialthat is selective toward nitrogen, and a plurality of valves 120 a-jconnected thereto for directing gas in and out of the beds 118 a, 118 b.As will be described in greater detail below, the valves 120 a-jpreferably operate in accordance with a novel PSA cycle which comprisesa six step/two bed process that includes a pressure equalization step inwhich a portion of the effluent product gas from one bed is diverted topressurize another bed in order to improve product recovery and reducepower consumption. One preferred embodiment of the PSA cycle comprisesthe following steps:

Step 1. Pressurize-Adsorbent Bed 118 a/Production-Adsorbent Bed 118 b

-   -   pressurizing adsorbent bed 118 a by directing feed gas into        adsorbent bed 118 a in the co-current direction at a feed        pressure of about 35 psia while simultaneously diverting oxygen        enriched product gas of higher pressure from adsorbent bed 118 b        into adsorbent bed 118 a in the counter-current direction until        pressures of the two beds 118 a, 118 b are substantially        equalized;    -   releasing product gas from adsorbent bed 118 b to a storage        vessel 124 while stopping the flow of feed gas from entering        adsorbent bed 118 b;

Step 2: Feed-Adsorbent Bed 118 a/Blowdown-Adsorbent Bed 118 b

-   -   feeding adsorbent bed 118 a with feed gas at a rate of about        4-8.5 slpm at a feed pressure of about 35 psia;    -   counter-currently releasing nitrogen enriched waste gas from        adsorbent bed 118 b to an exhaust muffler 122;

Step 3: Feed and Production-Adsorbent Bed 118 a/Purge-Adsorbent Bed 118b

-   -   releasing product gas from adsorbent bed 118 a to the storage        vessel 124 while continuing to feed adsorbent bed 118 a with        feed gas at a rate of about 4-8.5 slpm. at a feed pressure of        about 35 psia;    -   purging adsorbent bed 118 b by releasing product gas from the        storage vessel 124 to adsorbent bed 118 b while continuing to        counter-currently release waste gas from adsorbent bed 118 b to        the exhaust muffler 122;

Step 4: Production-Adsorbent Bed 118 a/Pressurize-Adsorbent Bed 118 b

-   -   continuing to release product gas from adsorbent bed 118 a to        the storage vessel 124 while stopping the flow of feed gas from        entering adsorbent bed 118 a;    -   pressurizing adsorbent bed 118 b by directing feed gas into        adsorbent bed 118 b in the co-current direction at a feed        pressure of about 35 psia while simultaneously diverting product        gas of higher pressure from adsorbent bed 118 a into adsorbent        bed 118 b in the counter-current direction until pressures of        the two beds 118 a, 118 b are substantially equalized;

Step 5: Blowdown-Adsorbent Bed 118 a/Feed-Adsorbent Bed 118 b

-   -   counter-currently releasing waste gas from adsorbent bed 118 a        to the exhaust muffler 122;    -   feeding adsorbent bed 118 b with feed gas at a rate of about        4-8.5 slpm at a feed pressure of about 35 psia;

Step 6. Purge-Adsorbent Bed 118 a/Feed and Production-Adsorbent Bed 118b

-   -   releasing product gas from adsorbent bed 118 b to the storage        vessel 124 while continuing to feed adsorbent bed 118 b with        feed gas at a rate of about 4-8.5 slpm at a feed pressure of        about 35 psia;    -   purging adsorbent bed 118 a by releasing product gas from the        storage vessel 124 to adsorbent bed 118 a while continuing to        counter-currently release waste gas from adsorbent bed 118 a to        the exhaust muffler 122;

The PSA cycle described above advantageously includes one or morepressure equalization steps (steps 1 and 4) in which already pressurizedproduct gas is released from one adsorbent bed to provide initialpressurization for another adsorbent bed until the two beds have reachedsubstantially the same pressure. The pressure equalization step leads toincreased product recovery and lower power consumption because itcaptures the expansion energy in the product gas and uses it topressurize other adsorbent beds, which in turn reduces the amount ofpower and feed gas required to pressurize each bed. In one embodiment,the two-bed PSA unit shown in FIG. 1 operating in accordance with theabove-described six-step/two-bed PSA cycle is capable of producingoxygen having a purity of at least about 87%, preferably between about87%-93%, with greater than about 31% recovery of oxygen from feed gas,more preferably greater than about 38% recovery. In operation, thevalves 120 a-j of the PSA unit 108 are controlled in a known manner toopen and close for predetermined time periods in accordance with theabove described PSA steps. Additionally, the valves 120 a-j arepreferably positioned upstream of the air stream produced by the fan 112across the compressor assembly 106 so as to not expose the valves 120a-j to portions of the air stream that are heated by the compressorassembly 106. In other embodiments, the system may utilize a vacuumswing adsorption (VSA) unit or a vacuum-pressure swing adsorption (VPSA)unit to produce the oxygen rich product gas.

As FIG. 1 further shows, the product gas produced by the PSA unit 108 isdelivered to a patient via the product gas delivery system 110. Theproduct gas delivery system 110 generally includes an oxygen sensor 126for monitoring the oxygen content of the product gas exiting the storagevessel 124, a delivery valve 128 for metering the product gas to thepatient, an in-line filter 130 for removing fine particulate in theproduct gas immediately prior to delivery to the patient, a conserverdevice 132 that controls the amount and frequency of product gasdelivered based on the patient's breathing pattern. In certainembodiments, the product gas delivery system may also incorporate a unitthat measures pressure within the storage vessel which in turn dictatesthe rate at which product gas is driven through the delivery valve.Preferably, product gas is delivered to the patient at a flow rate ofabout 0.15-0.75 slpm at about 90% oxygen content. In one embodiment, thesystem 100 also includes a microprocessor control 134 for collecting andrecording data on system performance or patient usage pattern and aninfrared port 136 for transmitting the data to a remote location.

FIG. 2 illustrates a gas fractionalization apparatus 200 of thepreferred embodiment, which is shown in the form of a portable oxygenconcentrator. As illustrated in FIG. 2, the apparatus 200 generallycomprises a chassis 202 (see also FIG. 3) and a shell 204 that togetherform a housing 206 in which various components are mounted. The chassis202 is removably attached to a base 208 of the housing 206. The base 208has a substantially planar exterior bottom surface adapted to restagainst a support surface such as a table or floor. The shell 204 of thehousing 206 further includes an upper wall 210 and side walls 212 a-d,each having at least one convex and/or concave section that provides acurvature to the wall so as to reduce coupling of sound or vibrationenergy generated by the components in the housing. Such curvature isalso effective to reduce constructive interference of the coupled energywithin the walls. Accordingly, the lack of planar sections in the walls210, 212 a-d of the housing 206 that are conducive to vibration reducesnoise induced by vibration. Moreover, the non-planar walls 210, 212 a-dalso serve to discourage users from setting the housing on its side orplacing it in any orientation other than the upright as the componentsinside the housing are designed to operate optimally in the uprightorientation, which will be described in greater detail below.

As shown in FIG. 3, the components in the housing 206 are structurallysupported by the chassis 202 and the chassis 202 is removably attachedto the shell 204. As such, the components can be assembled outside theconfines of the shell 204. Also, the shell can be conveniently removedto provide access for testing, repair, or maintenance of the components.Additionally, the housing 206 is preferably separated into twocompartments 300, 302 by a partition 304. The partition 304 inconjunction with an air flow system to be described in greater detailbelow significantly inhibits migration of thermal energy from the secondcompartment 302 to the first compartment 300. Preferably, heat sensitivecomponents are placed in the first compartment 300 and heat generatingcomponents are mounted in the second compartment 302 so as to thermallyisolate the heat sensitive components from the heat generatingcomponents for optimal system performance.

FIG. 4 provides a detailed view of the chassis 202, as seen without thecomponents. As shown in FIG. 4, the chassis 202 contains a number ofpre-formed structures configured to receive and support the differentcomponents in the housing. Three circular recess 400 a-c are formed in afirst base portion 402 of the chassis 202 for mating with a PSA unit.Three corresponding divots 404 a-c are also formed in the first baseportion 402 immediately adjacent each respective recess 400 a-c. Thedivots 404 a-c extend laterally into each respective recess 400 a-c todirect gas flow in and out of the PSA unit in a manner to be describedin greater detail below. As such, the chassis serves as a manifold ofsorts for routing gases to and from the PSA unit. An annular compressormount 406 extends upwardly from a second base portion 408 of the chassis202 to provide an elevated mounting surface for a compressor assemblyand define an opening 410 sufficiently large to receive a portion of theassembly. As will be described in greater detail, the compressor mount406 is configured to support the compressor assembly in a manner suchthat transfer of vibrational energy from the compressor assembly to thehousing is reduced. As also shown in FIG. 4, an oblong slot 412 and abail 414 are formed adjacent the compressor mount 406 for receiving andsecuring a battery. In one embodiment, electrical mating contacts areformed in the slot 412 for connecting the battery to operatingcircuitry. In one embodiment, a battery circuit is mounted on the bottomof the slot which can also contain a IRDA transmitter/receiver.Moreover, the chassis 202 can also be fit with notches to receive andsupport the bottom of the partition.

Preferably, at least some of the above-described structures of thechassis 202 are integrally formed via an injection molding process so asto ensure dimensional accuracy and reduce assembly time. Thesepre-formed structures in the chassis advantageously facilitate assemblyof the components and help stabilize the components once they areassembled in the housing. In one embodiment, the chassis serves thefunction of providing an intermediary vibration isolation to thecompressor and motor. As shown in FIG. 4, the chassis has bottom mountsor vibration isolation feet 407 that are configured to engage with thebottom of the shell. Preferably, screws are inserted through the bottomof the shell and into the bottom of the vibration feet 407. In anotherembodiment, the chassis further comprises an integrated muffler forexhaust gas. Preferably, a recess is formed below the battery slot inwhich felt or other porous material is placed. As will be described ingreater detail below, an exhaust tube from the PSA unit is preferablyported directly into this recess and the felt serves to break up noisecoming from the release of pressurized waste gas.

FIG. 5 provides a detailed view of the components in the firstcompartment 300 of the housing 206. As shown in FIG. 5, the firstcompartment 300 generally contains an air intake 502, an intake filter504, and a PSA unit 506. The air intake 502 is an elongated tube coupledto the intake filter 504 and extending downwardly therefrom to receiveintake air. The intake filter 504 comprises a cylindrical shaped filterthat is preferably capable of removing particles greater than about 0.1microns from the intake air with about 93% efficiency. Moreover, theshape, density, and material of the intake filter 504 can be selected toprovide the filter with acoustic properties so that the filter can alsoserve as an intake muffler. As will be described in greater detailbelow, the intake filter 504 is in fluid communication with a compressorsystem and supplies the compressor system with filtered intake air. Boththe air intake 502 and the intake filter 504 are preferably mounted inthe first compartment 300 of the housing 206 so as to avoid drawinghigher temperature air produced by components in the second compartmentinto the system.

As FIG. 5 further shows, the PSA unit 506 generally includes a pair ofadsorbent bed columns 508 a, 508 b, a product gas storage column 510,and an integrated manifold 512 for controlling fluid flow to and fromthe columns 508 a-b, 510. Each adsorbent bed column 508 a-b comprises anelongated housing containing a nitrogen-selective adsorbent materialsuch as zeolite. The adsorbent bed columns 508 a-b are adapted to removenitrogen from intake air in a known manner in accordance with a PSAcycle so as to produce an oxygen rich product gas. The product gasstorage column 510 comprises an elongated housing adapted to receive andstore the oxygen rich product gas. In one embodiment, the product gasstorage column 510 also contains an adsorbent material capable ofholding a higher molar density of the product gas than an equivalent gasfilled chamber at equal pressure. As shown in FIG. 5, all three columns508 a-b, 510 are mounted side by side in the housing 206. Preferably,the columns 508 a-b, 510 have substantially the same length so that theintegrated manifold 512 can be mounted horizontally on the upper end ofthe columns 508 a-b, 510.

As will be described in greater detail below, the integrated manifold512 contains a plurality of integrated flow passages formed in a singleplane that permit fluid to flow to and from the columns 508 a-b, 510.The integrated manifold 512 also has a plurality of solenoid valves 514positioned in a single plane that control the flow of the fluid to andfrom the columns 508 a-b, 510 during a PSA cycle. As shown in FIG. 5,the integrated manifold 512 is mounted on the upper end of the columns508 a-b, 510 in a manner such that the integrated flow passages in themanifold are in fluid communication with openings in the upper end ofeach column. While the manifold 512 is positioned on only the upper endof the columns, gas flow from the manifold can enter the column housingthrough either the upper or lower end due to a novel single-ended columndesign to be described in greater detail below. In one embodiment, thevalves 514 of the manifold 512 contain a plurality of contact pins 516adapted for direct contact with a circuit board in a manner to be shownin greater detail below. A circuit board controlling the valves can bemounted directly on top of the manifold 512 without additional wires,which advantageously simplifies the assembly process and also allows forthe construction of a more compact device.

In one embodiment, an oxygen sensor 518 is mounted on the integratedmanifold 512 and ported directly into a product gas flow passage in themanifold 512. The oxygen sensor 518 is configured to measure the oxygenconcentration in the product gas using a galvanic cell or other knowndevices. Mounting the oxygen sensor 518 directly on the integratedmanifold 512 results in a more compact assembly as it eliminates the useof tubing and connectors that are typically required to interconnect theoxygen sensor to the PSA unit. Moreover, it also places the oxygensensor 518 closer to the product gas stream, which is likely to improvethe accuracy and response time of the sensor. In another embodiment, abreath detector 520 is also ported into the integrated manifold 512. Thebreath detector 520 generally comprises one pressure transducer thatsenses pressure change in the product gas downstream of the productdelivery valve (shown schematically in FIG. 1) caused by inhalation andexhalation of the patient so that the gas delivery frequency can beadjusted accordingly. The breath detector 520 may also include a secondpressure transducer that senses the storage vessel pressure which isused to drive the delivery of the product to the patient through theproduct delivery valve. The breath detector 520 ports directly into themanifold instead of tapping into the product line downstream, whichobviates the need of additional tubing connections and reduces the riskof leakage.

One of the key factors in creating a usable portable concentrator islong battery life. Battery life can be extended in several ways. Forexample, it can be extended by decreasing the power consumption of theconcentrator while maintaining an acceptable performance level, andallowing for a wider range of battery voltage, such that theconcentrator can continue to operate even after the battery voltagestarts to decrease. Certain preferred embodiments of the presentinvention incorporate a Pulse Width Modulation (PWM) current controlsystem to accomplish both lower power consumption and a wider range ofbattery voltage operation.

An oxygen concentrator typically includes flow control valves, such assolenoid type valves. Existing portable concentrators typically actuatethe valves by applying a control voltage, which is at one level for ON(typically open valve) and another for OFF (typically closed valve).Such voltage controlled systems rely on well controlled voltage levels,with the ON level typically about 12 volts or more. However, in reality,many solenoid valves are actually actuated by current flow, and a highcurrent is required to open the valve, but a much lower current isrequired to maintain the valve in the open position.

Referring to FIG. 5A, the valves 120 a-n are actuated by a two stage PWMcontrolled current source 522. In one embodiment, the controller 134provides a digital control signal, preferably about 5 volts, a pulsetrain of variable duty cycle, which enables the current source. In thefirst stage, the current is controlled to a preset value for a presettime period so as to limit the voltage across the valve to a level whichwill be sufficient to guarantee rapid actuation while preventingexcessive current. In the second stage, a preset current level maintainsactuation of the valve while using minimum current. As is known in theart, varying the duty cycle essentially varies the amount of time thecircuit is on, so PWM circuits can run on less power than always ON orOFF voltage controlled circuits, which allows for a much wider range ofsupply (battery) voltage. In addition, for valves 120 a-n, the currentrequired to actuate the valve corresponds to one value of the dutycycle, while the lower current to maintain actuation corresponds to alower value of duty cycle. Thus the controller can achieve lower powerconsumption by reducing the duty cycle to the maintenance level to keepthe valve open (or closed) once the valve is actuated. Valves whichoperate similarly, except ON corresponds to closed valve, are alsocontemplated by the invention.

The fan 112, typically used for cooling, may also be actuated with a PWMcurrent source. The power draw of the fan circuit will be less with aPWM implementation. However the savings in power may not be worth theincreased circuit complexity for all applications.

The compressor 114 may also be actuated with a PWM current source. Inone embodiment, a speed sensor monitors the speed of the compressor. Theflow rate of the concentrator is preferably determined by the speed ofthe compressor. In one embodiment, the concentrator has selectable flowrate settings which correspond to duty cycle settings for the PWMcurrent source which powers the compressor. However, particularly whenthe concentrator is pressurizing, the load on the compressor istypically not constant. Therefore the controller can monitor the speedsensor and maintain the compressor speed substantially constant byadjusting the duty cycle controlling the current source to compensatefor variation in the speed sensor output.

Advantageously, the PSA unit 506 has many novel features which,individually and in combination, contribute to a lighter, more compactand reliable apparatus. As shown in FIG. 5, the PSA unit 506 is mountedin the first compartment 300 which is thermally isolated from other heatgenerating components in the housing 206. Thermal isolation of the PSAunit 506 substantially prevents heat degradation of the valves 514 andother components in the unit. The PSA unit 506 is also configured withintegrated gas flow passages so as to substantially eliminate the use offlexible tubing, which in turn reduces the number of potential leakpoints. Moreover, the PSA unit 506 is designed to operate with a single,generally planar integrated manifold mounted horizontally on one end ofthe columns. The single manifold design reduces the amount of space thePSA unit occupies inside the housing and also reduces potential leakpoints. Additionally, the PSA unit 506 is configured to directly connectto a circuit board without additional wires, which further conservesspace and simplifies assembly.

FIG. 6 provides a detailed view of the adsorbent bed columns 508 a, 508b of the PSA unit, illustrating the novel single-ended column designbriefly described above. As shown in FIG. 6, the column 508 a generallyincludes an elongated adsorbent housing 602 having an upper end 604 anda lower end 606, each defining an opening through which gas can flow inand out of the housing 602. The column 508 a further includes anintegrated feed tube 608 extending from the upper end 604 of the housing602 to the lower end 606. The feed tube 608 provides a gas passagewaybetween the manifold and the housing 602 such that gas from the manifoldcan be routed through the feed tube 608 into the lower end 606 of thehousing 602 and vice versa. This design eliminates the need of a secondmanifold for directing gas into the lower end 606 of the housing 602 andallows all flow passages in the manifold to be co-located in a singleplane, which significantly reduces the number of tubing connections andpotential leak points in the unit.

The feed tube 608 preferably has a relatively small internal diameter tosubstantially minimize head space. It is generally recognized that thefeed passage in a PSA unit represents head space, which is undesirableas it penalizes system performance. In one embodiment, the feed tube 608has an internal diameter of about 0.125 inch and the adsorbent housing602 has a diameter of about 1.5 inch. Moreover, the adsorbent housing602 and the feed tube 608 are preferably integrally formed in anextrusion process so as to eliminate the use of flexible tubing andreduce potential leakage. In certain embodiments, the adsorbent bedcolumn 508 a further includes a plurality of threaded mounting members610 positioned adjacent the adsorbent housing 602 for mating with screwsthat attach the column 508 a to the chassis and manifold. The threadedmounting members 610 are preferably co-extruded with the housing 602 andthe feed tube 608 so as to simplify part construction.

As also shown in FIG. 6, the adsorbent bed housing 602 contains anadsorbent material 612, an upper and a lower restraining disk 614 a, 614b for inhibiting movement of the adsorbent material 612, a spring 616that applies pressure across the upper restraining disk 614 a to keepthe disk 614 a in position. In one embodiment, the adsorbent material612 comprises a granular material such as zeolite that can be easilydislodged. The restraining disks 614 a-b are preferably comprised of afrit material that can also serve as a filter for gross particulate,such as dislodged zeolite. Each restraining disk 614 a-b has a diameterselected to form an interference fit with the internal walls of thehousing 602 and has a thickness of at least about 0.2 inch, to providesome resistance to tilting of the disk, which may lead to leaks ofparticulate. The thickness of the disk 614 a-b coupled with the natureof the frit material provide a tortuous path for particulate to travelthrough, which increases the effectiveness in trapping the particulateas compared to conventional paper filters. As also shown in FIG. 6, theupper restraining disk 614 a is pressed against the adsorbent material612 by the spring 616. The spring 616 is preferably a wave springconfigured to apply substantially uniform pressure across the surface ofthe upper restraining disk 614 a, so as to substantially inhibit thedisk from tilting.

As also shown in FIG. 6, the adsorbent bed column 508 a further includesannular gaskets 616 a, 616 b positioned adjacent to and in sealingengagement with the ends 604, 606 of the column 508 a to contain thepressurized gases therein. In one embodiment, each annular gasket 616a-b further comprises an integrally formed filter portion 618 a, 618 bfor filtering smaller particulate that cannot be captured by therestraining disks 614 a-b. Preferably, the filter portion is capable offiltering particles greater than about 70-120 microns. In oneembodiment, the gasket 616 a-b is made of a silicone material and thefilter portion 618 a-b comprises a woven fabric, woven screen, or thelike that is cast or molded together with the gasket. In anotherembodiment, the gasket 616 a-b and filter portion 618 a-b for all threecolumns of the PSA unit are injection molded as a single piece as shownin FIG. 6. Preferably, the filter portion 618 a-b is embedded in thegasket 616 a-b so as to facilitate placement of the filter portion andensure a reliable seal between the gasket and the filter portion.Moreover, openings 620 are formed in each gasket 616 a-b to accommodateopenings in the feed tubes and the threaded mounting members.

FIGS. 7A and 7B provide schematic illustrations of the adsorbent bedcolumn 508 a in combination with the chassis 202 and the manifold 512,showing the manners in which gas flow is directed in and out of thecolumn 508 a in accordance with the single-ended column design. As shownin FIG. 7A, feed gas 702 is directed from a feed stream 704 in themanifold 512 into an upper opening 706 of the feed tube 608. The feedgas 702 travels downwardly through the tube 608 and is diverted by adivot 404 a in the chassis 202 into a recess 400 a underneath the lowerend 606 of the adsorbent housing 602. The divot 404 a, which ispre-formed in the chassis 202, advantageously serves as a lateral gasflow passageway so as to eliminate the need of any flexible tubing onthe lower end of the column, which in turn simplifies assembly andreduces potential leak points. The feed gas 702 flows upwardly from therecess 400 a through the lower end 606 of the housing 602 and upwardlythrough the adsorbent material contained in the housing 602. Theadsorbent material selectively removes one or more components in thefeed gas 702 in a known manner to form a product gas 708. The productgas 708 flows out of an upper end 604 of the housing 602 into a productstream 710 in the manifold 512. FIG. 7B shows the manner in which purgegas is directed in and out of the column. As shown in FIG. 7B, purge gas712 from a product stream 714 in the manifold 512 is directed throughthe upper end 604 of the housing 602 downwardly into the housing 602 toflush out the gas therein. The purge gas 712 exits the lower end 606 ofthe housing 602 and is channeled through the divot 404 a. The divot 404a directs the purge gas 712 to flow into a lower opening 716 of the feedtube 608. The purge gas 712 exits the feed tube 608 through its upperopening 706 and enters a waste stream 718 in the manifold 512. As FIGS.7A and 7B illustrate, the single-ended column design in conjunction withthe divot formed in the chassis allow gas from a single-planed manifoldto enter and exit the adsorbent housing through either the upper orlower end of the housing.

FIG. 8 provides a detailed view of the integrated manifold 512 of thePSA unit. As shown in FIG. 8, the integrated manifold 512 generallyincludes an upper plate 802 and a lower plate 804, each having groovesformed in an inner surface thereof. The grooves of the lower plate alignwith those of the upper plate so as to form fluid passages in themanifold 512 when the upper plate 802 is affixed to the lower plate 804.The fluid passages may include feed gas pathways, waste gas pathways,and gas pathways interconnecting the adsorbent columns. The specificpattern of the fluid passages in the manifold can vary, depending on theparticular application, although the passages of the preferredembodiment correspond to the circuit of FIG. 1. As also shown in FIG. 8,the upper plate 802 has a feed gas inlet 812 through which pressurizedair from the compressor system is directed into the manifold 512. Thelower plate 804 has a waste gas outlet 814 through which exhaust gas isexpelled from the manifold 512 and a plurality of openings to connectthe fluid passages with the adsorbent columns. Solenoid valves 816 aremounted on an upper surface 818 of the upper plate 802 in a known mannerto control the flow of fluid between the fluid passages and the PSAcolumns. Bores 820 are also formed in the upper and lower plates 802,804 for receiving fasteners used to mount the plates together and ontothe PSA columns. In one embodiment, the plates 802, 804 of the manifold512 are made of a plastic material formed by injection molding andlaminated together via an adhesive bond applied in a vacuum. Whencompared to conventional laminated manifolds that are typicallyconstructed of machined metal plates, the integrated manifold 512 formedby injection molding is advantageously lighter and less costly tomanufacture.

FIG. 9 schematically illustrates a water trap system 900 integrated inthe manifold 512 for removing moisture from the feed gas prior todelivery to the columns. As shown in FIG. 9, the water trap system 900generally includes an integrated water trap 902 formed in the manifold512 and in fluid communication with a feed gas pathway 904. The watertrap 902 is adapted to trap condensed water 906 in the feed gas bygravity so as to prevent the water from reaching the adsorbent bed 908.Preferably, the water trap 902 is located in a waste gas pathway 910such that expelled waste gas carries the condensed water out through theexhaust.

In one embodiment, the water trap 902 is configured as a recess in thelower plate 804 of the manifold 512, extending downwardly from a sectionof the feed gas pathway 904 located in the upper plate 802. The watertrap 902 is positioned at a lower elevation relative to the feed gaspathway 904 so as to substantially prevent trapped water 908 fromre-entering the feed gas pathway 904. In certain embodiments, a baffle912 is positioned in the feed gas pathway 904 to divert the feed gasflow downwardly into the water trap 902 so that the gas is required torise upwardly to return to the feed gas pathway 904, which substantiallyprevents any condensed water from being carried past the water trap bythe feed gas flow. As also shown in FIG. 9, the water trap 902 is inline with the waste gas pathway 910 located in the lower plate 804 ofthe manifold 504 so that the water trap 902 can be purged by waste gasflowing through the pathway 910. In one embodiment, the water trap 902is located in center of a three way junction formed by the airflowpassages to and from the feed valve, the exhaust valve, and theconnection to the top of the column.

In operation, feed gas 914 enters the manifold 512 through the feed gasinlet 812 in the upper plate 802 and is directed through a solenoidvalve 816 into the feed gas pathway 904. The feed gas 914 flows acrossthe recessed water trap 902 such that condensed water 906 in the feedgas 914 settles into the water trap 902 by gravity while the lightercomponents continue along the pathway 904 into the adsorbent bed 908.Preferably, the water trap 902 containing the condensed water 906 issubsequently purged by gas in the waste gas pathway 910. It will beappreciated that the integrated water trap system is not limited to theabove-described embodiment. Any integrated water trap system thatencompasses the general concept of forming an integrated gas flow pathhaving a lower region where light air flows past and moisture aircondenses due to gravity are contemplated to be within the scope of theinvention.

FIG. 10 schematically illustrates a piloted valve system 1000 integratedin the manifold 512 for providing quick release of pressurized gas fromthe adsorbent columns during a PSA cycle. It is generally recognizedthat the efficiency of a PSA cycle benefits from fast release of thepressurized gas within the adsorbent columns during the blow down andpurge steps. However, the solenoid valves controlling gas flow from thecolumns to the waste gas pathway are typically limited in orifice sizewhich in turn results in restricted flow and slowed release of the gaswithin the columns. To increase the flow capacity, the piloted valvesystem 1000 shown in FIG. 10 utilizes a solenoid valve to drive a muchlarger piloted valve that is embedded in the manifold and controls thewaste gas flow to and from the columns.

As shown in FIG. 10, the piloted valve system 1000 generally includes asolenoid valve 1002, an air chamber 1004 in fluid communication with thesolenoid valve 1002, and a piloted valve 1006 that can be actuated bythe solenoid valve 1002 through the air chamber 1004. The piloted valve1006 preferably comprises a diaphragm 1006 positioned between the airchamber 1004 and a waste gas pathway 1008. Pressure differences betweenthe air chamber 1004 and the waste gas pathway 1008 mechanically deflectthe diaphragm 1006 to open or close the waste gas pathway 1008 to gasflow. Preferably, the diaphragm 1006 has a natural resiliency such thatit is deflected away from the waste gas pathway 1008 when the airchamber 1004 is not pressurized.

In one embodiment, the diaphragm 1006 is seated in a recess 1010 thatextends downwardly from an exterior surface 1012 of the upper plate 802.An insert 1014 is mounted in the recess 1010 above the diaphragm 1006and flush with the exterior surface 1012 of the plate 802. The diaphragm1006 has an outer rim 1016 that sealingly engages with an inner surface1018 of the insert 1014 so as to form the air chamber 1004 as shown inFIG. 10. The insert 1014 contains a plurality of openings 1020 that arein fluid communication with the air chamber 1004. The solenoid valve1002 is mounted above the insert 1014 and controls gas flow through theopenings 1020 to the air chamber 1004.

As also shown in FIG. 10, the waste gas pathway 1008 is formed in thelower plate 804 of the manifold and in contact with the diaphragm 1006through an opening 1022 formed in the inner face 808 of the upper plate802. To close the waste gas pathway 1008 from gas flow, the diaphragm1006 is deflected toward a baffle 1024 positioned in the waste gaspathway 1008 and sealingly engages with the baffle 1024 so as to blockoff a pathway 1026 between the diaphragm and the baffle. To open thewaste gas pathway 1008, the diaphragm 1006 is deflected away from thebaffle 1024 so as to allow gas to flow through the pathway 1026 and outthe exhaust. It will be appreciated that the pathway 1026 controlled bythe diaphragm 1006 provides a much large flow capacity for waste gasthan the orifices in the solenoid valves.

In operation, pressurized purge gas 1028 from the adsorbent column flowsinto the opening 1022 in the upper plate 802 and pushes the diaphragm1006 away from the baffle 1024 so as to open the path 1026 between thediaphragm 1006 and the baffle 1024 for gas flow. After the purge gas isreleased through the exhaust, a portion of the feed gas is directed intothe air chamber 1004 via the solenoid valve 1002 to push the diaphragmagainst the baffle 1024 so as to close the path 1026 therebetween.Advantageously, the piloted valve system 100 allows waste gas to bereleased from the column through a much larger opening than the orificescontained in the solenoid valves and does not consume additional spaceas the valves are all incorporated in the manifold.

FIG. 11 provides a detailed view of the components inside the secondcompartment 302 of the housing 206. As shown in FIG. 11, the secondcompartment 302 generally contains an air circulation fan 1102, abattery 1104, and a compressor assembly 1106. In one embodiment, the fan1102 comprises a blower or other device used for forcing aircirculation. The battery 1104 is preferably a lithium ion battery havinga rated life of at least 2 hours. In certain embodiments, the batterymay also comprise a fuel cell or other transportable electric powerstorage device. The compressor assembly 1106 includes a compressor 1108,a driving motor 1110, and a heat exchanger 1112. In one embodiment, thecompressor 1108 is preferably a non-reciprocating compressor such as ascroll compressor or a radial compressor and the motor 1110 ispreferably a DC brushless motor. In certain embodiments, the compressor1108 can also be a vacuum pump or a combination of a vacuum pump and acompressor. The heat exchanger 1112 can be in the form of aluminumcoiled tubes or other common heat exchanger designs. In one embodiment,the heat exchanger 1112 has an inlet 1114 and an outlet 1116. The inlet1114 is in fluid communication with the compressor 1108 for receivingfeed gas therefrom and the outlet 1116 is connected to the PSA unit fordelivery feed gas thereto.

As also shown in FIG. 11, the compressor 1108 rests on an upper surface1118 of the compressor mount 406, which is elevated above the base 208of the housing. The driving motor 1110 attached to the compressor 1108extends into the opening 410 in the compressor mount 406 and remainssuspended therein. Moreover, the heat exchanger 1112 is positioned abovethe compressor 1108 and under the fan 1102. Preferably, the fan 1102directs an air flow against the heat exchanger 1112 to facilitatecooling of the feed gas therein. As also shown in FIG. 11, the battery1104 is mounted on the battery bail 414 via three pairs of guide rails1120 formed on the battery and adapted to mate with the battery bail414. The distance between the guide rails 1120 becomes progressivelyshorter from bottom to top, with the topmost pair forming the tightestfit with the bail 414. This facilitates mounting of the batteryparticularly for those with impaired dexterity. When the battery 1104 isin position, the topmost guide rails are held firmly by the bail 414while a lower section 1130 of the battery 1104 is held firmly by themated electrical connectors formed in the battery slot 412.

In one embodiment, a compressor restraint 1122 is connected between thecompressor 1108 and the chassis 202 to secure the compressor 1108 to thehousing 206. Preferably, the compressor restraint 1122 comprises anelastic tether that fastens the compressor 1108 to the chassis.Preferably, the chassis is fit with grooves for engaging with thecompressor restraint. In one embodiment, the compressor restraint 1122comprises two elongated legs 1124 a, 1124 b spaced apart in the middleand joined together in an upper end 1126 a and a lower end 1126 b. Theupper end 1126 a is removably attached to the compressor 1108 and thelower end 1126 b removably attached to the chassis 202. Moreover, theelongated legs 1124 a, 1124 b preferably have preformed bends whichextend away from each other. These bends can be pressed toward eachother to straighten the legs and increase the overall length of thecompressor restraint 1122 so as to facilitate mounting and removal ofthe compressor restraint. Preferably, the compressor restraint does notsubstantially exert active force on the compressor assembly when thehousing is in its upright position so as to reduce vibration couplingfrom the compressor to the chassis.

In another embodiment, a vibration damping member 1128 is interposedbetween the compressor mount 406 and the compressor 1108 to furtherreduce transfer of vibrational energy from the compressor to thehousing. As shown in FIG. 12, the vibration damping member 1128comprises a grommet 1202 configured to mate with the annular compressormount so as to provide a vibration damping mounting surface for thecompressor system. Preferably, the grommet 1202 is made of a resilientsilicone material such as sorbothane and configured to absorb lowvibrational frequencies produced by the compressor. In one embodiment, afirst set of ribs 1204 are formed along the periphery of an uppersurface 1206 of the grommet 1202 and configured to absorb vibration fromthe compressor. In another embodiment, a second plurality of ribs 1208are formed on an inner surface 1210 of the grommet 1202 and configuredto absorb vibration from the motor. The ribs 1204, 1208 substantiallyreduce the amount of vibration transferred to the grommet 1202 which isin contact with the compressor mount. The compressor advantageouslyrests on the grommet without being pressed against the chassis duringnormal operations and is restrained by the compressor restraint onlywhen the apparatus is tipped over on its side. The vibration dampingmember 1128 is advantageously configured to reduce transfer of vibrationenergy, particularly low frequency vibration, from the compressor systemto the housing, thus reducing noise created by vibration of the housing.

In addition to vibration control features, the apparatus alsoincorporates one or more thermal management systems to provide coolingfor temperature sensitive components inside the housing and facilitateheat dissipation. FIG. 13 illustrates a thermal management system of onepreferred embodiment adapted to provide cooling for the battery. Athermal sleeve 1302 is positioned around the battery 1104 to isolate airsurrounding the battery 1104 from higher temperature air in the secondcompartment 302 of the housing. A lower end 1304 of the thermal sleeve1302 is configured to mate with the battery slot 412 so as to close offthe lower opening of the sleeve and form a compartment or air pocket forthe battery. A cooling gas is preferably directed into the space betweenthe thermal sleeve 1302 and the battery 1104 to facilitate dissipationof heat generated by the battery and also to insulate the battery fromheat generated by other components in the housing.

In one embodiment, a conduit 1306 extends from the exhaust outlet 814 ofthe PSA unit 506 to an opening 1038 in the battery slot 412. The conduit1306 directs exhaust gas 1312 from the PSA unit 506 into the spacebetween the thermal sleeve 1302 and the battery 1104. Since the exhaustgas is typically cooler than ambient air surrounding the batterycompartment, it serves as an efficient source of cooling air for thebattery. The exhaust gas enters the thermal sleeve 1302 from the loweropening 1308 in the battery slot 412 and circulates out of the upper end1310 of the thermal sleeve 1302.

As also shown in FIG. 13, a circuit board 1314 is mounted horizontallyon the PSA unit 506, above the valves 816 on the manifold 512. Thecircuit board 1314 comprises control circuitry which governs theoperation of the PSA unit, alarms, power management system, and otherfeatures of the apparatus. As described above, contacts on the circuitboard 1314 are in direct electrical contact with mating contacts 516 onthe valves 514 of the PSA unit 506, which conserves space and eliminatesthe need for wiring connections. In one embodiment, the circuit board1413 has small through-hole connectors that align with the location ofvalve pins to establish electrical interconnection.

As will be described in greater detail below, the circuit board 1314 islocated in the path of a directed air flow inside the housing so as tofacilitate heat dissipation of the circuits during operation. Moreover,although the control circuitry is substantially entirely within thefirst compartment 300, the circuit board 1314 extends horizontally fromthe first compartment 300 to the second compartment 302, substantiallycovering the upper openings of both compartments so as to inhibitmigration of higher temperature air from the second compartment 302 intothe first 300. In one embodiment, foam material is placed between theouter edges 1316 of the circuit board 1314 and the inner walls of thehousing to form an air seal which further inhibits migration of airbetween the compartments 300, 302. In another embodiment, the circuitboard 1314 is shaped to mirror the cross-sectional contour of thehousing so as to ensure an effective seal between the circuit board 1314and housing.

FIG. 14 schematically illustrates a thermal management system of anotherpreferred embodiment, which is configured to provide a continuous flowof cooling air across the components inside the housing. As shown inFIG. 14, ambient air 1402 is drawn into the housing 206 through an airinlet 1404 by the fan 1102. The air inlet 1404 is preferably located ina lower portion of the sidewall 212 c adjacent the first compartment300. The ambient air 1402 is direct to flow through an air flowpassageway 1406 generally defined by the walls of the housing and thecomponents therein. The air flow passageway 1406 is preferably acircuitous path extending from the air inlet 1404, through the first andsecond compartments 300, 302, to an air outlet 1408 located in a lowerportion of the sidewall 212 a adjacent the second compartment 302.Preferably, the ambient air is directed to flow across the firstcompartment, which contains temperature sensitive components, beforeentering the second compartment which contains heat generatingcomponents. As will be described in greater detail below, the thermalmanagement system utilizes the air circulation fan 1102 in combinationwith the configuration of the housing and placement of componentstherein to produce a one-way flow passageway for air from inlet tooutlet. As such, heated air is not re-circulated back into the systemand the components are cooled by a continuous stream of external air.

In one embodiment, the air flow passageway 1406 has an upstream portion1408 and a downstream portion 1410. The upstream portion 1408 includes avertical path 1406 a generally defined by the PSA unit 506 and thesidewall 212 c of the housing 206 followed by a horizontal path 1406 bgenerally defined by the circuit board 1314 and the upper wall 210. Thedownstream portion 1410 includes a vertical path 1410 a generallydefined by the partition 304 and the battery 1104, a horizontal path1410 b generally defined by the compressor assembly 1106 and the base208 of the housing, and followed by another vertical path 1410 c definedby the battery 1104 and the sidewall 212 a. Air in the upstream portion1408 of the passageway 1406 preferably has a lower temperature than airin the downstream portion 1420 where most heat generating components arelocated. Temperature sensitive components such as the valves 514 andelectrical components disposed on the circuit board 1314 areadvantageously disposed in the upstream portion 1408, thereby exposingthe valves and components to a continuous stream of incoming coolingair, which reduces their thermal load. Preferably, the upstream portion1408 of the air flow passageway 1406 is thermally isolated from thedownstream portion 1410 by the partition 304 and the circuit board 1314in conjunction with a directed air flow described below.

As also shown in FIG. 14, the fan 112 is located in the downstreamportion 1410 of the air flow passageway 1406 immediately above thecompressor assembly 1106. The fan 112 generates a downward air streamdirectly against the compressor assembly 1106 to facilitate heatdissipation of the heat exchanger and compressor. The air stream flowspast the compressor assembly 1106 through the downstream portion 1410 ofthe air passageway 1406 and exits the housing 206 through the air outlet1408. The fan 1102 is advantageously positioned to focus a cooling airstream directly on the heat generating components inside the housing.Moreover, portions of the air stream warmed by the compressor assemblyare not re-circulated inside the housing, which substantially minimizesincreases in the ambient temperature therein and improves coolingefficiency. The air stream generated by the fan 1102 creates a negativepressure in the upstream portion of the passageway 1406, which drawsambient air through the passageway 1406 from the first compartment 300to the second compartment 302 as shown in FIG. 14. Although someturbulence of the air may occur downstream of the fan, the air pathconfiguration permits substantially one way air flow along the pathbetween the intake and the fan.

In certain embodiments, noise reduction features are also implemented inthe apparatus. As shown in FIG. 14, a series of sound absorbing baffles1412 are positioned along the air flow pathway 1406 to reduce noisecaused by the air flow inside the housing. Moreover, the air flowpassageway is configured with a circuitous path so as to further abatethe noise generated by the air flow. The circuitous path advantageouslyprovides for air movement through the housing, but makes it difficultfor sound to propagate or reflect off internal surfaces of the housingand make its way out of the housing.

FIG. 15 schematically illustrates the manner in which intake air 1500 isprocessed through the components of the apparatus. As shown in FIG. 15,intake air 1500 is drawn through the air intake 502, through the airfilter 504 into an inlet port 1404 of the compressor 1108. Air ispreferably drawn into the compressor air intake at a flow rate of nogreater than about 15 slpm so as to maintain a low noise level and lowpower consumption throughout the system. The air is pressurized by thecompressor 1108 and delivered to the heat exchanger 1112 through thecompressor outlet 1406. The pressurized air is cooled by the heatexchanger 1112 and then supplied as feed gas to the PSA unit 506. Feedgas is directed through the inlet port 812 of the PSA unit 506, intoadsorbent columns 508 a-b to produce a product gas in accordance with aPSA cycle, preferably the six step/two bed cycle described above.Product gas from the adsorbent columns 508 a-b flows into the storagecolumn and is delivered to the patent through an outlet port 1408 in themanifold 512 connected to the storage column. Preferably, the productgas is delivered to the patient at a flow rate of between about 150ml/minute and 750 ml/minute and having an oxygen concentration of atleast 87%, more preferably between 87%-93%.

FIG. 16A shows the apparatus as fully assembled in the form of aportable oxygen concentrator unit 1600. The unit 1600, including thehousing and components therein, has a combined weight of preferably nothan about 10 pounds and produces a noise level of no greater than about45 dB external to the unit. As shown in FIG. 16A, an air scoop 1602 isintegrally formed in the sidewall 212 c of the shell 204 adjacent theair outlet 1408 to channel air flow out of the housing 206. A similarair scoop is also formed in the sidewall adjacent the air inlet (notshown) to channel ambient air into the housing. As described above, thesidewalls 212 a, c of the housing have a curved configuration so as todiscourage users from resting the housing against the sidewall, whichcan block the air inlet or outlet.

As also shown in FIG. 16A, a user interface panel 1602 containing aplurality of system controls 1604 such as flow rate and on-off switchesis integrally formed in the shell 204. In some embodiments, an I/O port1606 is preferably formed in the user interface panel 1602. The I/O portallows data transfer from the unit to be performed simply by using acomplementary device such as a palm desktop assistant (PDA) or laptopcomputer. Moreover, an in-line filter system 1608 is also formed in theshell 204 to filter product flow in line prior to delivery to thepatient. As will be described in detail below, the in-line filter system1608 is integrated in the shell 206 of the unit so as to provide easyaccess to the filter without requiring opening of the shell.

As shown in FIG. 16B, the in-line filter system 1608 includes an annularchamber 1610 formed in the shell 204 and a fitting 1612 that engageswith the chamber 1610 from outside of the shell. The chamber 1610 has aseat portion 1612 configured to receive a disk filter 1614 and athreaded portion configured to engage with the fitting 1612. Preferably,the chamber 1610 is molded into the shell 204 and oxygen product insidethe housing is ported to the chamber. In one embodiment, the disk filter1614, preferably a 10 micron or finer filter, is held in compression inthe seat portion 1612 of the chamber by the fitting 1612, whichthreadably engages with the chamber 1610 from outside of the shell. Inanother embodiment, the fitting 1612 also contains a hose barb 1618 usedto connect the cannula. Advantageously, the disk filter 1614 can beserviced by simply unscrewing the fitting 1612, replacing the filter1614, and then re-screwing the fitting 1612 without ever having to openthe housing of the unit. As shown in FIG. 16C, the unit 1600 alsoincludes a removable hatch 1620 that provides simplified access to thecircuit board 1314 inside the housing 206 and the internal connectionsto the oxygen product line and power input.

FIG. 17 schematically illustrates a satellite conserver system 1700 thatcan be used in conjunction with the oxygen concentrator unit 1600 todeliver oxygen to users. It is generally recognized that oxygenconcentrators deliver a finite rate of oxygen product which must bemetered to the user through a conserving device. A conserving device istypically mounted inside the concentrator and includes a breath sensorthat senses breath inhalation of the user to determine the timing andquantity of each bolus delivery. The sensitivity of the breath sensor issignificant to the efficacy of the conserving device. As such, mostconserving devices require that users use no longer than a 10 feet tubeconnected to the nasal cannula to ensure that the conserving deviceinside the concentrator can accurately sense the breath of the user.

The satellite conserver 1700 is configured to substantially remove theconstraint imposed by the short tube requirement and allow users thefreedom to move in a much larger area around the portable concentrator.As shown in FIG. 17, the satellite conserver 1700 includes a small,lightweight conserving device 1702 for delivering oxygen rich productgas to users in metered amounts in a known manner in response to sensedbreath. The conserver 1700 includes a breather sensor 1701 for sensingthe user's breath and a delivery valve 1703 for delivering oxygen to theuser. In one embodiment, the conserving device 1702 utilizes a breathrate algorithm that delivers a nearly constant amount of oxygen perminute, regardless of the breath rate of the patient. As such, patientswho take more breaths within a give time period receive the same amountof oxygen as those who take less breaths. In another embodiment, theconserving device adjusts the bolus volume based on the flow settingrather than the breathing rate. In yet another embodiment, theconserving device 1702 can be fit with a second pressure sensor, whichdetects the pressure in the input line from the concentrator. Thedelivery valve timing can be adjusted based on the sensed pressure atthe end of the input line such that a higher pressure corresponds to ashorter valve open time and a lower pressure corresponds to a longervalve open time.

As also shown in FIG. 17, the conserving device 1702 is adapted to beworn by the user or positioned adjacent to the user so that breathsensing functions can be performed proximate to the user even if theconcentrator unit is far away. Thus, the sensitivity of the breathsensor is not compromised even if the user is far way from the unit. Thesatellite conserver 1700 further includes flexible tubing 1704connecting the conserving device 1702 to the hose barb fitting 1612 onthe concentrator 1600. In one embodiment, the tubing 1704 is preferablybetween 50 to 100 feet, which provides users a much greater radius ofmobility. When the satellite conserver 1700 is in use, the breathdetector mounted inside the housing of the concentrator is disabled. Asalso shown in FIG. 17, the satellite conserver can be worn on the personby a clip 1706 attached to the conserving device 1702. The satelliteconserver advantageously permits the user to move around the vicinity ofthe concentrator, preferably in at least a 50 to 100 feet radius,without detracting from the efficacy of the unit.

To further add to the convenience of the patient, it is desirable to addin some level of patient control of the concentrator functionality inthe satellite conserver 1700. For cases where the patient is using along hose between the satellite conserver and the concentrator, it isadvantageous to allow the patient to change some settings without thenecessity of returning to the concentrator base unit. One of the mostuseful settings to adjust at the conserver is flow rate. If the patientfor some reason requires a higher flow rate due to increased exertionwhile operating at a large distance from the base unit, it would be aproblem to require the patient to return to the base unit to obtain ahigher flow of oxygen rich air. As shown in FIG. 17A, the satelliteconserver device 1700 of certain preferred embodiments includes apatient interface 1708 that allows the patient to change flow rate. Oneembodiment of this interface is a flow setting knob which selects fromseveral flow rate settings. In one embodiment, the knob interfaces to atiming circuit 1710. The timing circuit 1710 controls how long a flowvalve 1712 is open. Thus when the breath sensor 1701 detects a breath,the flow valve 1712 is opened for a time determined by the knob setting.In certain embodiments, the conserver requires a battery 1714 to powerthe timing circuit sensor 1710 and valve 1712.

FIG. 18A schematically illustrates a mobility cart 1800 configured totransport an oxygen concentrator unit for users traveling away fromhome. As shown in FIG. 18A, the mobility cart 1800 includes a generallyrectangular frame 1802 attached to a plurality of wheels 1804 so as topermit rolling movement of the frame 1802 over the ground. As also shownin FIG. 18A, the frame 1802 has a support portion 1806 adapted forreceiving an oxygen concentrator unit and a handle portion 1808extending upwardly from the support portion 1806 for users to hold whenmoving the cart. The support portion 1806 preferably contains acompartment 1810 configured to seat the oxygen concentrator and at leasttwo slots 1812 configured to seat and secure spare batteries. In oneembodiment, a battery bail 1814 is placed in each slot 1812 for securingthe batteries in the manner described above. In another embodiment, asmall recess 1816 is formed in the back of the compartment 1810 forholding the satellite conserver, spare cannulas or filter.

As also shown in FIG. 18A, the mobility cart 1800 further includes anon-board power supply 1818 that is attached to the frame 1802 portion.Preferably, the power supply 1818 has an AC power input and is adaptedto power charging terminals fitted in each battery slot 1812 and aterminal fitted in the compartment for charging the battery within theconcentrator. In one embodiment, the cart also has an adapter plug 1820that extends from the power supply 1818 and mates with theconcentrator's DC power input jack. The power supply 1816 is preferablysufficient to power both battery chargers while simultaneously poweringthe concentrator unit and charging the battery mounted inside the unit.Each battery preferably has a rated life of at least 2 hours so that theuser is able to enjoy continuous use of the concentrator unit for atleast six hours without an external power source. In one embodiment, thepower supply is cooled by a fan mounted on the frame portion 1802. Inanother embodiment, the frame portion has recesses through which watermay drain out without damaging the parts. The cart 1800 can furthercomprise an integrated power cord and/or retractable power cord that isadapted to be plugged into a wall.

FIG. 18B illustrates the manner in which the oxygen concentrator 1600and spare batteries 1822 are positioned in the mobility cart. As alsoshown in FIG. 18B, the handle 1808 has two telescoping rails that can beextended and retracted. When the handle 1808 is the fully retractedposition as shown in FIG. 18B, the mobility cart 1800 preferably has aheight of about 14-18 inches and can be stored in a small area such asunder an airplane seat. In one embodiment, the mobility cart isstructured such that the concentrator, when sitting in the cart,interfaces closely with seals positioned on the frame of the cart at theair intake and exhaust ports. As such, airflow coming into or out of theconcentrator actually travels through the frame in some manner, addingextra sound attenuation by increasing the tortuosity of the flow path.Moreover, an auxiliary fan or blower mounted in the cart can also beused to circulate this air further. Advantageously, the mobility carthas integrated battery chargers and power supply incorporated in oneunit so as to obviate the need for users to pack power supplies orexternal chargers when traveling with their concentrator. Moreover, thecart provides a single compact unit in which all oxygen concentratorrelated parts can be transported, which allows users greater ease ofmobility when traveling.

FIGS. 19A-E illustrate a battery pack 1900 configured to provideelectrical power to a portable oxygen concentrator of one preferredembodiment of the present invention. As shown in FIG. 19A, the batterypack 1900 has a generally U-shaped body 1902 containing one or morebatteries therein, a handle portion 1904 configured to facilitateinstallation and removal of the battery pack 1900, and a contactprotrusion 1906 configured to electrically couple the battery pack 1900to power contacts on the portable oxygen concentrator. As will bedescribed in greater detail below, the U-shaped body 1902 facilitatesproper alignment of the battery pack 1900 to the oxygen concentratorduring installation and also helps heat dissipation of the batteriesenclosed therein.

FIG. 19B provides an exploded view of the battery pack 1900. As shown inFIG. 19B, the battery pack 1900 generally includes a casing 1908 havingtwo opposing sections 1910 a, 1910 b and a plurality of battery cells1912 disposed within the casing 1908. The two opposing sections 1910 a,1910 b of the casing 1908 can be joined together by snap fitting,adhesive or other suitable methods. As also illustrated in FIG. 19B, thebattery cells 1912 are stacked in a two deep and side-by-side arrayalong a non-linear path, which arrangement facilitates heat dissipationof the batteries without substantially increasing the footprint of thebattery pack. In one embodiment, twelve rechargeable lithium ion batterycells 1912 are supported by a base structure 1914 inside the casing1908. Preferably, the cells are grouped into four sets, with each setcontaining three cells. The sets are connected in parallel while thecells within each set are connected in series. The battery cells 1912are also electrically connected to a power contact 1916 that extendsoutwardly through an opening in the casing 1908 for mating with contactson the portable oxygen concentrator. Details related to electricalconnection of the cells in the battery pack are generally known topersons skilled in the art and thus are not shown and described here.Moreover, it will be appreciated that the batteries used can alsoinclude a variety of other known storage cell technology, such aslithium polymer cells, nickel cadmium batteries, and nickel metalhydride batteries.

Referring to FIG. 19C, the battery pack 1900 also includes a pluralityof guide rails 1918 formed on an outer surface 1920 of the battery pack1900. As previously discussed, the guide rails 1918 are configured toengage with a mounting structure on the oxygen concentrator, such as thebail 414 shown in FIG. 4. Preferably, the battery pack 1900 has threepairs of guide rails 1918 with the distance between each pair becomingprogressively shorter from bottom to top, with the topmost pair formingthe tightest fit with the bail. In one embodiment, the distance betweena pair of guide rails is between about 2 to 2.5 inches. As also shown inFIG. 19C, the handle portion 1904 extends from an upper surface 1922 ofthe battery pack 1900. Preferably, the handle 1904 has a sufficientlylarge surface area configured for a person to easily grab onto and exerta force against in the vertical direction. In one embodiment, the handleportion 1904 has an elongated concave section 1924 configured to receivea person's fingers so that the person can easily grab onto and lift thebattery pack out of the oxygen concentrator. Preferably, the handleportion 1904 has a length of about 4.125 inches or less, a width ofabout 0.75 inch or less, and a height of about 0.75 inch or less

FIG. 19D provides a cross-sectional view of the battery pack 1900. Asshown in FIG. 19D, the battery pack 1900 has a generally U-shaped bodyincluding a center portion 1926 forming the bight of the U and two endportions 1928 a, 1928 b projecting from opposite ends of the centerportion 1926 forming the legs of the U. The general U-shaped contour ofthe battery pack 1900 is further illustrated in FIG. 19E. Referring toFIG. 19E, the battery pack 1900 has a top portion 1930, a bottom portion1932, an exterior side portion 1934, and an interior side portion 1936.The interior side portion 1936 includes at least a portion of theinterior sidewall 1938 of the battery pack 1900. The contour of thebattery pack 1900 can be further defined by a plurality of axes.

As shown in FIG. 19E, the battery pack 1900 has a longitudinal axis1940, a transverse axis 1942, a lower transverse axis 1944, a centrallower lateral axis 1946 and a first and second end lower lateral axes1948 a, 1948 b. The longitudinal axis 1940 is defined as an axis thatextends through the top and bottom portions 1930, 1932 and through theinterior sidewall 1938 of the battery pack in a manner such that it isgenerally parallel to the side portions 1934, 1936 and end portions 1928a, 1928 b of the battery pack 1900. The transverse axis 1942 is definedas an axis that intersects the longitudinal axis 1940 and extendsthrough the end portions 1928 a, 1928 b in a manner such that it isgenerally parallel to the side portions 1934, 1936 and top and bottomportions 1930, 1932 of the battery pack 1900. The lower transverse axis1944 is defined as an axis that is parallel to the transverse axis 1942,intersects the longitudinal axis 1940 and passes through the bottomportion 1932 of the battery pack 1900. The central lower lateral axis1946 is defined as an axis that is orthogonal to the longitudinal axis1940 and intersects both the longitudinal axis 1940 and the lowertransverse axis 1944. The first and second end lower lateral axes 1948a, 1948 b are defines as axes that are parallel to the central lowerlateral axis 1944, intersect the lower transverse axis 1944, and passthrough the respective end portions 1928 a, 1928 b.

In a preferred embodiment, the distance between the exterior surfaces1950 a, 1950 b of the end portions 1928 a, 1928 b measured along thelower transverse axis 1944 is about 4.25 inches or less; the distancebetween the exterior surfaces 1952 a, 1952 b of the side portions 1934,1936 along the central lower lateral axis 1946 is about 1 inch or less;the distance between the exterior surfaces 1954 a, 1954 b of the firstend portion 1928 a along the first end lateral lower axis 1948 a isabout 1.5 inches or less; and the distance between the exterior surfaces1956 a, 1956 b of the second end portion 1928 b along the second endlateral lower axis 1948 b is also about 1.5 inches or less.

As also shown in FIG. 19E, the contact protrusion 1906 has a rectangularshape generally defined by two pairs of opposing sidewalls 1958, 1960.The sidewalls 1958, 1960 preferably extend outwardly from the bottomportion 1932 by about ⅜ inch or more. The length of the sidewalls 1958that are parallel to the lower transverse axis 1944 is about 1.5 inch orless. The length of the sidewalls 1960 that are parallel to the centrallower lateral axis is about 0.5 inch or less. The contact protrusion1906 is configured be received into a recess on the oxygen concentratorand mate with power contacts therein to electrically connect the batterypack to the concentrator. Alternatively, the contact protrusion 1906 canalso be received into a recess formed in a mobility cart or in aseparate battery charger to mate with power contacts therein.Preferably, the battery pack 1900 is symmetrical about the center lowerlateral axis 1946 but asymmetrical about the lower transverse axis 1944.The asymmetrical configuration functions as a key for users to properlyalign the battery pack in the oxygen concentrator.

Although the foregoing description of certain preferred embodiments ofthe present invention has shown, described and pointed out thefundamental novel features of the invention, it will be understood thatvarious omissions, substitutions, and changes in the form of the detailof the system, apparatus, and methods as illustrated as well as the usesthereof, may be made by those skilled in the art, without departing fromthe spirit of the invention. Consequently, the scope of the presentinvention should not be limited to the foregoing discussions.

1. A battery pack for providing electrical power to a portable oxygenconcentrator, comprising: a generally U-shaped body defined by a centerportion and end portions, said center portion forms the bight of the Uand said end portions form the legs of the U; a top portion, a bottomportion, an exterior side portion and an interior side portion; alongitudinal axis, said longitudinal axis is an axis that extendsthrough the top and bottom portions and generally parallel to the sideand end portions and passing through a wall of the interior sideportion; a transverse axis, said transverse axis is an axis that extendsthrough the end portions and parallel to the side, bottom, and topportions and intersecting the longitudinal axis a lower transverse axis,said lower transverse axis is an axis that is parallel to the transverseaxis and passing through the bottom portion and intersecting thelongitudinal axis; a central lower lateral axis, said central lowerlateral axis is an axis orthogonal to the longitudinal axis andintersecting both the longitudinal axis and the lower transverse axis; afirst and second end lower lateral axes, said first and second end lowerlateral axes are axes which are parallel to the central lower lateralaxis and intersect the lower transverse axis and which pass throughrespective end portions; a contact protrusion having two pairs ofopposing sidewalls, at least one of the sidewalls extends from thebottom portion by about ⅜ or more, said contact protrusion having afirst sidewall that is generally parallel to the lower transverse axisand has a length of about 1.5 inches or less, said contact protrusionhaving a second sidewall that is generally parallel to the central lowerlateral axis and has a length of about 0.5 inch or less; wherein thedistance between the exterior surfaces of the end portions measuredalong the lateral transverse axis is about 4.25 inches or less; whereinthe distance between the exterior surfaces of the side portions alongthe central lower lateral axis is about 1 inch or less; wherein thedistance between the exterior surfaces of the first end portion alongthe first end lateral lower axis is about 1.5 inches or less; whereinthe distance between the exterior surfaces of the second end portionalong the second end lateral lower axis is about 1.5 inches or less; andwherein the battery pack is substantially symmetrical about the centrallateral lower axis and asymmetrical about the lower lateral transverseaxis.
 2. The battery pack of claim 1, further comprising a handleextending upwardly from an upper surface of the body of the batterypack.
 3. The battery pack of claim 2, wherein said handle has anelongated concave portion.
 4. The battery pack of claim 1, furthercomprising at least one pair of guard rails positioned on the interiorside portion of the battery pack, said guard rails are configured toengage with a mounting surface on the portable oxygen concentrator. 5.The battery pack of claim 4, wherein said guard rails are configured toengage with a battery bail.
 6. The battery pack of claim 5, wherein saidbattery bail is mounted on the oxygen concentrator.
 7. The battery packof claim 5, wherein said battery bail is mounted on a mobility cart. 8.The battery pack of claim 4, wherein the distance between the guardrails is between about 1 to 1.5 inches.
 9. The battery pack of claim 1,further comprising a casing and a plurality of battery cells enclosedtherein, wherein at least a portion of the battery cells are arranged ina side-by-side array along a non-linear path.
 10. The battery pack ofclaim 1, wherein the contact protrusion is configured to engage with arecess formed in the portable oxygen concentrator.
 11. A battery packfor providing electrical power to a portable oxygen concentrator,comprising: a plurality of battery cells; an asymmetrical housing havinga U-shaped cross-section, wherein said housing encloses the batterycells therein and permits said battery cells to be positioned in aside-by-side arrangement along a non-linear path inside said housing; ahandle portion extending from an upper surface of the housing; and acontact protrusion extending from a lower surface of the housing formating with power contacts on the oxygen concentrator.
 12. The batterypack of claim 11, wherein the battery cells are selected from the groupconsisting of lithium ion cells, lithium polymer cells, nickel cadmiumcells and nickel metal hydride cells.
 13. The battery pack of claim 11,wherein the footprint of the battery pack has a length that is less thanabout 4.25 inches and a width that is less than about 1.5 inches whenthe battery pack is mounted in an upright position in the oxygenconcentrator.
 14. The battery pack of claim 1, wherein the contactprotrusion extends from a lower surface of the housing by about ⅜ inchor more.